The present invention relates generally to forming apparatus, and more particularly to apparatus for electromagnetically forming or swaging cooperating portions of conductive work pieces by magnetic pulse means so as to connect the work pieces together.
Various methods and apparatus are known for forming or swaging conductive materials through the use of electromagnetic pulses. Conventionally, such apparatus establishes a magnetic field of sufficently high intensity and duration to create a high amperage electical current pulse which when passed through a conductor in the form of a coil creates a pulse magnetic field of high intensity in the proximity of one or more selectively positioned conductive work pieces. A current pulse is thereby induced in the work pieces which interacts with the magnetic field to produce a force acting on the work pieces. In the case of connecting telescoped portions of conductive work pieces, this force or magnetic pressure is made of sufficient magnitude to cause a desired deformation of the cooperating work pieces so that one piece is swaged to the other, the manner of deformation being generally dependent upon the shape or configuration of the magnetic field and the position of the work pices relative to the field.
The known apparatus for electromagnetic forming or swaging two work pieces into fixed relation typically employs a coil operative to surround the portions of the conductive work pieces to be formed or swaged. Many electromagnetic forming operations make use of solenoid compression coils in conjunction with shapers to concentrate the electromagnetic field pressure in the work area. When using such a forming coil with certain types or shapes of work pieces, a problem frequently arises in the ability of the work pieces to be inserted within the coil aperture defining the forming area or in withdrawal of the connected work pieces from the coil aperture. This is a particular problem when the work piece or assembly being formed has an enlarged or irregular configuration or has flanged ends which make it difficult, if not impossible, to insert or pass the work piece through a generally circular coil aperture by axial movement of the work piece. For example, one configuration which does not lend itself to removal from conventional forming coil apertures by axial movement of the formed work piece is a ring or circular shape. To alleviate this problem, electromagnetic forming apparatus have been developed which employ coil halves formed of conductive material and so arranged as by hinging, to be moveable between open positions enabling an irregular shaped work piece to be placed between the coil halves after which they are closed to provide a current path around the work piece. While the electrical efficiency of such hinged coil or shaper arrangements has been generally adequate, they do not lend themselves to high production rates in that the moveable one of the coil or shaper halves must generally be disconnected from the pulse power circuit during movement to enable insertion and removal of the work piece.